Replaces the Family One, Ecotec and HF V6 engine familiesAre designed to be most advanced, efficient and refined in their classShare a standardized 98mm Bore Centers, 88 mm Bores and 88 mm StrokesSpan 1.6 to 6.4 liters with 3, 4, 6 and 12-cylinder variants

Ground Breaking Technologies

Homogeneous Charge Compression Ignition (HCCI) – At low engine speeds and load, Varitec engines operate without using the spark plug to ignite the fuel-air mixture. Instead, it increases the effective compression ratio and adjust the mixture to cause spontaneous ignition very much like a diesel engine. This enables up to a 20% increase in brake specific fuel consumption at cruising speeds. Varitec engines are capable of operating in HCCI mode between 1500 rpm 3000 rpm.

Tricam VVTLD – One Concentric and One regular cam shafts per bank affords Variable Valve Timing Lift and Duration control of the intake valves, as well as exhaust cam phasing. The ability to continuously alter the intake cam duration and timing allows the engine to negate up to 30% of the compression stroke and operate in Atkinson Cycle (or Miller Cycle) mode when maximum power is not needed. Atkinson Cycle operation creates a longer power stroke relative to the compression stroke improving energy recovery and fuel economy – Miller Cycle is similar concept but applied with forced induction. This ability to alter the effective compression stroke also allows for the effective compression ratio to be dynamically adjusted which is a necessary ingredient to enabling HCCI operation. Effective displacement of Varitec engines is variable from 70% to 100% of their swept volume during operation, whereas Effective Compression can be adjusted from 9.4 to 13.5:1 (8.2 to 11.7:1 on turbocharged applications).

Flywheel Integrated Generation and Starting (FIGS) – Varitec Engines do not have a belt driven alternator and a regular starter motor. Instead, they carry a 30 mm thick Generator-Motor in place of the flywheel. A 1.5 kW version provides basic electric generation as well as engine starting. As a standard feature, Varitec engines have the ability to automatically stop the engine when it is idled for over 5 seconds at standstill and restart it when the driver lifts the foot off the brake pedal. This feature is enabled when the transmission setting is in ECO mode. In vehicles equipped as mild Hybrids, a 15 kW Flywheel Integrated Generator-Motor offers up to 15 bhp / 80 lb-ft in electric assist in addition to electric generator and starting. Both the 1.5 kW and 15 kW FIGS operate on long life Lithium-Iron-Phosphate batteries. The basic Generator-Starter operates on a 12.8V electrical system, whereas the assist capable 15kW system runs at 115.2 V.

Refinement Tuning – The Varitec family is designed from the ground up to be the most refined engines in their class. This is achieved through four main avenues. The first is that all Varitec engines (except the V12 which is naturally balanced) feature balance shaft(s). This includes the 60 deg V6es – a configuration which traditionally do not receive a balancer because the 1st order vibrations are considered mild. The Second is an extensive strengthening of the engine blocks through the incorporation of isogrid girders in the exterior of the block and using a one piece lower block with cast in place bearings. Thirdly, the engines make extensive use of Helmholtz resonators and strategically placed insulation around the noisy direct injectors. Finally, because the Varitec family has the ability to adjust its effective compression, the engine automatically switches to the lowest compression ratio and maximum intake stroke negation during idle and low loads when not operating within the HCCI regimes. Incidental to the reduction in compression ratio is a reduction in combustion noise.

Dwight, what about at least a V8 for the trucks and high performance vehicles?

The reason there is no V8 is that the V8s remain on the Pushrod Small block architecture -- fortified with cam-in-cam Dual Independent VVT, Direct Injection and Cylinder Deactivation of course. A 6.2 liter Gen V small block so configured will probably be make 450~470 hp on premium and probably around 420 hp on regular. To get to a similar output, a 4.3 liter "Varitec" V8 will need to be making over 100 hp per liter. This means either forced induction or revving into the 7500~8000 rpm range. The engine will be more expensive, bulkier, heavier and probably no more efficient on fuel... which then beckons the question why? What does that get you? A bit more refinement? The balance shafted 3.2 60 deg V6es already get you plenty of that for the mainstream models, whereas a bi-turbo V12 caps off the ultimate luxury-performance class.

Instead of a high revving V8 or bi-turbo V8, I think the Corvette, ATS-V and CTS-Vs are better served with a compact, light, affordable and efficient Pushrod V8. The trucks even more so by a 87 octane compatible version of the small block as well as the 4.5 & 6.6 liter Duramax Diesels. In fact, it is probably not a bad idea to add a 4.6 liter V6 based off the 6.2 V8 for lower end trucks -- more power, more accessible torque than Varitec V6; much less expensive and less worrisome on maintenance than a bi-turbo V6. A 4-engine Pushrod lineup looking something like this...

Strictly from a component standpoint, we are talking about a more complex intake cam assembly -- concentric shaft and an additional cam phaser -- and a set of cylinder pressure sensors. Probably less than a turbocharger, intercooler and their plumbing. Most of this is going to be R&D and proofing costs.